The illustration of prayer that Our Lord uses here is that of a good child asking for a good thing. We talk about prayer as if God heard us irrespective of the fact of our relationship to Him (cf. Matthew 5:45). Never say it is not God’s will to give you what you ask, don’t sit down and faint, but find out the reason, turn up the index. Are you rightly related to your wife, to your husband, to your children, to your fellow-students – are you a "good child" there? "0 Lord, I have been irritable and cross, but I do want spiritual blessing." You cannot have it, you will have to do without until you come into the attitude of a good child.